The present invention relates to apparatus for manipulating flat elongated envelopes, particularly for opening envelopes which contain strips or webs of photosensitive material.
It is known to confine strips of photosensitive material in flat elongated envelopes or sheaths which are made of paper and/or synthetic plastic material. It is also known to place such strips between metallic foils, particularly between foils which are made of or contain lead. The dimensions of the envelopes are selected in such a way that the strips of photosensitive material are confined therein with minimal clearance or with no clearance at all, i.e., each envelope constitutes an elongated flat sheath-like body having two panels which are joined to one another along both marginal portions of the confined strip. Such envelopes are often employed for confinement of X-ray films, particularly X-ray films which are intended for use in the industry. An envelope of considerable length is normally stored in convoluted condition on the core of a reel, and requisite lengths of the envelope are severed from the stored supply when the need arises. The length of detached portions of the envelope varies within a very wide range, e.g., between 0.5 m and 50 m, depending on the intended use of the strips therein. The strips are exposed while confined in the envelopes, and the envelopes are thereupon opened in a dark chamber so as to allow for removal of the exposed strips from their interior. The opening involves severing of the envelopes along the two marginal portions of the confined strips of exposed photosensitive material, i.e., in the regions where the panels of the envelopes are joined to each other and define pronounced fold lines or creases along the respective edges of the strips. Thus, the edges of the strips extend all the way to the respective fold lines. This complicates the opening of envelopes, especially if they contain strips of the type wherein the emulsion extends all the way to the edges. For example, such types of photosensitive material are used for the making of mammographs. Manual extraction of exposed strips from intact envelopes, i.e., from envelopes which are not severed along one or both edges of the strips, is practically impossible, especially if the strips are long, because the strips are confined between the respective panels with little clearance or with no clearance at all. As a rule, the envelopes are introduced into a dark chamber and are cut open lengthwise by hand. Such operation is time consuming and the operator is likely to scratch the exposed photosensitive material during opening and separation of the envelopes.